Figure 9.

Myogenin and Myf5 colocalize in vivo and co-occupy promoters with MyoD. (A) Myf5 and myogenin colocalize on promoters during embryonic development. Chromatin immunoprecipitation (ChIP) analysis was performed on skeletal muscle from E18.5 embryos. The immunoprecipitated DNA was purified and amplified with primers specific to the promoter of leiomodin 2 (Lmod2) and desmin (Des). The fold enrichment values were calculated as described in Methods. (B) Myf5, myogenin and MyoD co-occupy promoters. Cross-linked extracts from myofibers in differentiation media for two days were immunoprecipitated with antibodies against the indicated antibody (1st IP) or IgG. The immunoprecipitated complexes were released and immunoprecipitated again with antibodies against the indicated antibody (2nd IP). The immunoprecipitated DNA was purified and amplified with primers specific to the promoters of Tnni2 and Des. Relative enrichment at the IgH locus was used to normalize the data. The fold enrichment values were calculated as described in Methods.